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This paper presents an experimental study on the mechanism of interaction between a cavitation bubble and an air bubble. The cavitation bubble was generated by means of the low-voltage discharge method, and the combination of high-speed photography and a pressure measurement system allowed for simultaneous observation and measurement of the evolution of the shock wave and the change in shock wave strength with the presence of the air bubble in the vicinity. The high-speed imaging revealed the predominant roles of the relative distance φ and relative size ε between the cavitation and air bubbles in the determination of the stratification effect that the air bubble exerted on the shock wave produced from the first collapse of the cavitation bubble. The pressure measurement indicated that, when the air bubble did not merge with the cavitation bubble, the aforementioned factors, together with the angle $\\alpha $ formed by the air bubble, cavitation bubble and the measuring point, would jointly affect the attenuation of the pressure peak and energy of the shock wave. Quantitatively, the attenuation magnitude was proportional to $a{(\\alpha \\varphi /\\varepsilon )^b}$, where the values of the coefficients a and b depended on whether the shock wave was stratified or not. When the cavitation bubble and the air bubble merged, the energy and the pressure peak of the shock wave decreased to less than 40 % of the values in the absence of the air bubble. With the new insight into bubble–bubble interaction mechanisms, the findings will facilitate a better understanding and development of cavitation utilization and prevention technology in water--air two phase systems.

The Anatolian Plateau, currently experiencing rapid uplift and westward escape, records both the termination of oceanic subduction and the conversion to continental collision. The crustal response to the transition of the subduction environment from eastern to western Anatolia can be inferred by the seismic velocity and attenuation structures. With this study, we construct a broadband Lg‐wave attenuation model for the Anatolian Plateau and use it to constrain lateral crust heterogeneities linked to this transition. Crustal Lg attenuation links late Cenozoic magmatism with asthenospheric upwelling by characterizing the lithospheric thermal structure. The widely distributed strong attenuation observed in eastern Anatolia may be related to the crustal partial melting due to mantle upwelling after the delamination and subsequent break‐off of the Bitlis slab. Lithospheric dripping in central Anatolia likely facilitates the mantle flows through the window between the Cyprus and Aegean slabs, which results in the piecemeal low QLg${Q}_{\\mathit{Lg}}$anomaly in central Anatolia. Plain Language Summary Different parts of the Anatolian Plateau are in different evolution stages between oceanic subduction and continental collision and currently undergoing plateau uplift and tectonic escape. The regional seismic velocity and attenuation can be used to characterize crustal partial melting and lateral heterogeneity, which can further identify the underlying subduction process. In this study, we construct a high‐resolution broadband Lg‐wave attenuation model for the Anatolian Plateau. Strong Lg attenuation in Anatolia correlates well with late Cenozoic magmatism distributions and can be an indicator of high temperature or partial melting in the crust. Combined with previous studies, we suggest that the mantle upwelling induced by the delamination of the Bitlis slab is likely reworking the crust in eastern Anatolia and is the cause of widespread thermal anomalies there. The lithospheric dripping process in central Anatolia may facilitate the mantle flows through the window between the Cyprus and Aegean slabs, and results in a piecemeal low QLg${Q}_{\\mathit{Lg}}$anomaly pattern in central Anatolia. Key Points A high‐resolution broadband Lg‐wave attenuation model is constructed for the Anatolian Plateau Widespread strong attenuation in the eastern Anatolian crust is likely related to slab delamination The circular‐shaped attenuation anomaly may result from slab tearing and lithospheric dripping beneath central Anatolia

Polyurethane foam has the characteristics of low density, nonlinear mechanics and energy absorption, and has been widely used in the research of shock wave attenuation. In order to realize the effective attenuation of the blast wave, the attenuation process of the shock wave in the medium is simulated by Autodyn. The impact ignition simulations were carried out for the Comp B impact ignite TNT under the bulkheads. The results show that the explosion-proof performance of the composite bulkhead is signi2icantly better than that of the single medium bulkhead. The combination of PR 6720 (polyurethane foam) and 45#steel can greatly attenuate the blast wave. The impact impedance matching relationship of the bulkhead and the medium on both sides should be used as an important design factor when designing the bulkhead.

In order to study the effect of the near-ground explosion of energetic materials (EMs) on the shell of a vertical incinerator, the effect of different explosion heights of EMs of 90 g TNT on the incinerator shell with different exhaust gas outlet diameters was numerically simulated in three dimensions using AUTODYN software. The simulation results showed that the maximum von Mises equivalent stress (mis. stress) of the shell occurred at the upper edge of the incinerator exhaust gas outlet. Furthermore, the maximum mis. stress of the shell increased with the decrease of the height from the TNT explosion center to the bottom of the shell and the increase of the exhaust gas outlet diameter of the incinerator. Importantly, the existence of the incinerator exhaust gas outlet and the constraint of the shell increased the critical height with the near-ground explosion effect compared to that of the unconstrained open environment (157 mm). The exhaust gas outlet diameter of the incinerator increased from 80 mm to 160 mm, and the critical height with near-ground explosion effect increased from 180 mm to 250 mm. In the design and application of vertical incinerators, the effect range of near-ground explosion can be reduced by reducing the diameter of the shell exhaust gas outlet and filling the bottom surface with a certain height of shock wave attenuation material.

Seismic coda wave attenuation (QC) reflects both intrinsic inelasticity and small‐scale heterogeneities in the Earth's crust, offering insights into its thermal state and structural complexity. Continental China, characterized by widespread plate boundary deformation, is among the most tectonically active regions globally. Using over a decade of data from the China National Seismic Network, we apply the Multiple Station and Multiple Event Method to estimate station‐side QC across 1–14 Hz, yielding high‐resolution maps that reveal block‐scale patterns aligned with tectonic boundaries. The Northeast, South, and North China blocks show consistently high QC values, while significantly lower values are observed in Xinjiang, Tibetan Plateau, and North–South Seismic Belt, consistent with theoretical expectations that low values are observed in active regions. Furthermore, we identify a negative correlation between QC and shear strain rate at higher frequencies, suggesting a fundamental link between attenuation and crustal stress heterogeneity.

Despite recent numerical simulations and limited laboratory studies highlighting the potential of semi-embedded seismic metamaterials (SEM) in attenuating Rayleigh waves, their real-world effectiveness remains unverified, particularly for Love waves. Love waves pose significant destructive risks to slender structures but have rarely been the focus of research. To address this gap, we present the first full-scale 2D field experiment on an SEM composed of an array of semi-embedded rubber column resonators. The experimental results reveal a global bandgap spanning 25-37 Hz and a localized bandgap at 37-42 Hz. At the central frequency of the global bandgap ( = 31 Hz), the attenuation reaches -9.3 dB for Love waves and -5.3 dB for Rayleigh waves, with the mitigation of Love waves being notably pronounced. Furthermore, our theoretical and experimental analyses provide novel mechanistic insights: the primary energy dissipation in flexible rubber resonators arises from the resonance of their exposed above-ground sections, while the underground buried parts introduce damping that moderately reduces the efficiency of surface wave attenuation. This pioneering full-scale on-site validation bridges the critical gap between simulation-based predictions and practical seismic protection systems, providing valuable reference for the engineering application of SEM, especially for mitigating destructive waves.

Sand walls have a good energy absorption and wave attenuation effect on explosion shock waves, which can also have an impact on the seismic waves generated by the evolution of shock waves. In order to study the effect of sand wall in energy absorption on the results of explosive ground motion, four repeated explosion experiments were conducted by using different sand wall configurations. A ground motion measurement system was designed to measure the velocity at different distances from the explosion center. The measurement and analysis results showed that under the action of the sand wall, the peak velocity and the total energy based on vibration velocity both significantly decreased, fully demonstrating the energy absorption and wave attenuation effect of the sand wall. The sand wall also has an impact on the cube root similarity rate, resulting in the distribution of ground motion parameters no longer strictly following this law, but the sand wall has no significant impact on the frequency distribution. Under different sand wall configurations, the circle shaped sand wall has a better energy absorption and wave attenuation effect, while the circle shaped sand wall with nested circle shaped ends can enhance the energy absorption and wave attenuation effect by 21%.

Balancing stress wave attenuation with structural integrity is recognized as a critical challenge for protective materials in underground defense systems. A novel high-titanium slag (HTS) concrete featuring multiscale pores is proposed to address this dilemma. Large-particle porous HTS aggregates are embedded into cement mortar, enabling mechanical robustness comparable to conventional concrete alongside significant stress wave dissipation. Wave scattering and gas–solid interfacial reflections are induced by the multiscale pore architecture, effectively attenuating energy propagation. A dense interface transition zone between HTS aggregates and the cement mortar is confirmed through microscopic characterization, ensuring structural coherence. Wave attenuation is revealed by Split Hopkinson Pressure Bar tests to primarily originate from pore-driven reflections rather than impedance mismatch. A groundbreaking strategy is offered for designing blast-resistant materials that harmonize dynamic energy dissipation with structural durability, advancing the development of resilient underground infrastructure.

A series of dynamic tests were carried out to investigate the effect of joint roughness on the wave energy attenuation in rock masses and estimate the relation between joint roughness and seismic quality factor of rock masses. The modified split Hopkinson pressure bar (SHPB) apparatus was adopted in this study, where the loading, input and output bars were made of gypsum. The propagation coefficient of the gypsum bars was measured from trial tests. According to the propagation coefficient of the gypsum bars, the strain, stress and particle velocity on the contact surfaces between the specimen and input/output bars were obtained from the test data recorded by the strain gauges. The specimens were prepared by a three-dimensional printer with plaster and binder. Each specimen modeled a rock mass with one joint with different roughness. The seismic quality factor of specimen is also estimated from the proposed approach of wave energy dissipation. The effects of joint roughness on the seismic quality factor of rock mass and the wave energy attenuation across the rock mass are analyzed from test results.

The attenuation of seismic waves in the Zagros region (southwestern Iran) was investigated using seismic waveforms collected from 2006 to 2019. The selected data set consists of 6421 local earthquakes (3 < ML < 5.5) recorded at a permanent network composed of 36 seismic stations. The quality factor of seismic body waves was estimated using the extended coda normalization method. Estimated values for Qp and Qs at five central frequencies (1.5, 3, 6, 12, 18 Hz) are Qp(r≤100km)=(57.3±3)f(0.71±0.11) and Qs(r≤100km)=(72±4)f(0.8±0.06), respectively. We used Wennerberg’s (Bull Seismol Soc Am 83: 279–290, 1993) method to separate intrinsic and scattering attenuation. This study suggests that the values of Qsc and Qi are close to coda attenuation, which may arise from the complex tectonic nature of the Zagros. The estimated results of coda wave attenuation show the same results as the intrinsic and scattering attenuation, which suggests that this is the main cause of the coda decay. According to our results, the attenuation of seismic waves in the Zagros area is significant due to geological features such as hidden faults, numerous fractures, a sedimentary layer, the Gachsaran Formation, and Hormuz salt. Spatial variation in Q values reveals that the attenuation is higher in the northern parts of the region than in the southern parts. The results of this study are compared to other seismically active areas.